Posterior osteotomy requires clear surgical plan, may limit complications vs. combined approach

It may limit complications vs. anterior osteotomy or combined anterior and posterior surgery in patients who undergo surgery for sagittal or coronal plane correction.

Posterior-based osteotomies encompass a spectrum of surgical techniques used for the correction of spinal deformity in the sagittal or coronal planes.

Sigurd H. Berven, MD, of the University of California, San Francisco, discussed the kinds of adult deformity cases in which he prefers posterior osteotomy over an anterior approach to achieve the spinal correction a patient needsat Spine Summit 2015: CNS/AANS Section on Disorders of the Spine & Peripheral Nerves Annual Meeting.

Sigurd H. Berven

“Osteotomies are the primary technique for realignment of the spine with significant deformity. Osteotomies encompass a spectrum of techniques that range from facet joint resection to resection of segments of the spinal column. The appropriate use of osteotomies requires a clear understanding of the flexibility of the spinal column, and a clear surgical plan to define the goals of correction of the spine,” Berven told Spine Surgery Today.

Focus on end goals

There is considerable variability in how a surgeon approaches patients with spinal deformity and an anterior or posterior approach is part of the variability, Berven said at the meeting.

He encouraged surgeons to think about the goals of realignment of a deformed spine, not only at the segmental level, but at the regional and global levels of the spine, as well. He said trying to get the lumbar lordosis to match the pelvic incidence is important.

“I think there are some real advantages to a posterior approach. In this instance through a single stage, single incision, with better pulmonary tolerance, and significantly less complications,...in many cases we can get very effective deformity correction with a posterior-only approach when we are using these osteotomies,” Berven said at the meeting.

The work of Frank J. Schwab, MD, has quantified the end goals of realignment with a correlation of the impact of spinal deformities on radiographic parameters, including the sagittal vertical axis, pelvic tilt and T1 tilt, according to Berven.

Flexibility a key factor

Berven said flexibility should be the number one factor when surgeons think about spinal osteotomy choices. A flexible curve, a very stiff curve or a rigid curve can directly affect the osteotomy chosen for a procedure. With advanced imaging, such as MRI or CT scans, or dynamic imaging, surgeons can get a better idea of how rigid the patient’s spine may be in the sagittal plane.

Among the types of posterior osteotomies Berven discussed were the pedicle subtraction osteotomy (PSO), which addresses segmental realignment when there is sharp, focal deformity in a rigidly fused spine, and the Ponte osteotomy for patients with flexible deformity with a mobile anterior column.

Figure 1. A 52-year-old man had a prior fusion from L4 to S1 as an adolescent for the diagnosis of dysplastic spondylolisthesis. Figure 2. The patient had an extension of his fusion to L1 posteriorly as seen in an MRI and CT image of his sagittal profile. Figure 3. This patient presented preoperatively with a severe sagittal plane deformity, back pain and bilateral leg pain to the L5 distribution.

Source: Berven SH

“In patients with bridging osteophytes or ankylosing spondylitis, the Smith-Petersen osteotomy may be useful if the spine can be mobilized with osteoclasis of the anterior column,” Berven said.

There is a continuum of posterior osteotomies and there are different grades of destabilization. Grades one and two are just resection of the posterior facet joint. Grades three and four are partial corpectomy and grades five and six are a vertebral column resection, he noted.

The Smith-Petersen osteotomy is also indicated for patients with prior fusions that need to be taken down if the anterior column is mobile, Berven said.

Three-column procedures

For transpedicular or three-column procedures, Berven uses a wedge resection as described by Thomasen. He also discussed an “eggshell” technique that involves decancellation, which was originally described by Charles F. Heinig, MD.

“Something I commonly use in my surgical technique is really eggshelling that bone. I can minimize blood loss with that,” he said.

Increased blood loss, deep infection and reduced lower-extremity motor function scores are among the complications that may be associated with more involved multi-column osteotomies. Therefore, surgeons need to guard against those risks, according to Berven.

Algorithm can help

For complicated three-level osteotomies, Berven uses a combination of the techniques. He discussed shortening the posterior column and fulcruming over the anterior longitudinal ligament. The three-column osteotomy tends to work best in patients with ankylosing spondylitis or a solid anterior column of the spine.

An algorithm developed by Lawrence G. Lenke, MD, may actually help surgeons decide which osteotomy to choose when it comes to their patients’ specific situation, according to Berven.

“Maybe we ought to be making the decision-making for an algorithm for our osteotomies with regard to surgeon experience, as well as flexibility of the curve. Simple facetectomies may be best for flexible deformity. But [for] a short sharp focal deformity, our VCR (vertebral column resection osteotomy) and PSO may be better options. The Ponte osteotomy is very useful for flexible anterior column, a transpedicular wedge resection for a patient with a circumferential fusion, and a vertebral column resection when you need to get trunk translation. That is the algorithm that worked best for patients with severe deformity,” he said. – by Susan M. Rapp and Robert Linnehan

References:
Berven SH. SRS Co-sponsored session — spine deformity: Osteotomies. Presented at: Spine Summit 2015: CNS/AANS Section on Disorders of the Spine & Peripheral Nerves Annual Meeting; March 4-7, 2015; Phoenix.
Thomasen E. Clin Orthop Relat Res. 1985;194:142-152.

For more information:
Sigurd H. Berven, MD, can be reached at UCSF Medical Center Spine Center, 400 Parnassus Ave., Third Floor, San Francisco, CA 94143; email: bervens@orthosurg.ucsf.edu.

Disclosure: Berven receives honoraria from Zimmer Biomet, DePuy Spine, Globus Spine, Medtronic and Stryker Spine. He has ownership interest in Providence Medical and Simpirica Spine and receives royalties from Medtronic.